A method of attaching an upholstery material to a cushion molding (cushion member), which is a representative of foamed moldings, for producing an automotive seat (hereinafter may be simply referred to as “seat”) includes a hog ring method in which the metal wires embedded in both a cushion member and an upholstery material are fixed by a metal ring; an adhesive method in which a cushion member and an upholstery material are fixed by an adhesive; and a method in which a hook surface fastener made of a woven or knitted fabric or plastics is embedded in a cushion member by a mold-in process and a loop surface fastener sewed on the back surface of upholstery material is fixed to the hook surface fastener by engagement.
Recently, an engaging member which is applicable to curved surfaces of seats for use in a surface fastener mold-in process is proposed.
For example, an engaging member which comprises a long flexible rod having a circular cross-section and mold-in hook engaging elements formed on the surface thereof is disclosed (Patent Document 1). Generally, the engaging member is integrally molded-in onto the bottom of narrow groove formed on the surface of a cushion member. An upholstery material is fixed to the cushion member by attaching loop engaging elements which correspond to the shape of the engaging member to the back surface of the upholstery material and then engaging the both engaging elements by pushing the loop engaging elements into the groove.
Various proposals are made on the loop engaging elements to be fitted to the upholstery material. For example, a loop engaging member comprising a flexible ribbon plate and loop engaging elements formed on one surface thereof is disclosed (Patent Document 2). Both the lengthwise extending ends of the loop engaging member are sewed to the superposed edge portions of two pieces of upholstery materials so that the loop engaging elements face outwardly. Then, the upholstery material is fixed to the cushion member by pushing the loop engaging elements facing outwardly into the groove.
In another proposed method of fixing an upholstery material to a cushion member, a cylindrical surface fastener is used, in which loop engaging elements are formed along the lengthwise direction partly on the surface thereof and a portion for fixing an upholstery material is formed along the lengthwise direction on the surface having no engaging element. The fixing portion extends outwardly and perpendicularly to the array of the loop engaging elements. Two pieces of upholstery material are fixed to the fixing portion by sewing at their edges and then the loop engaging elements are pushed into the groove of a cushion member to fix the upholstery material to the cushion member (Patent Document 3). The engaging member of Patent Document 3 easily bends in conformity with the curved engaging member on the bottom of curved groove of the cushion member.
Generally, the mold-in hook engaging elements are formed in a narrow groove on the surface of cushion member. In case of using any of the engaging members holding the upholstery material proposed by Patent Documents 1 to 3 for fixing the upholstery material to the cushion member, it is extremely difficult to precisely align the starting end of the loop engaging elements in the engaging member holding the upholstery material to the starting end of the hook engaging elements on the cushion molding. If both the starting ends are positioned distortedly or out of line, the upholstery material is wrinkled to spoil its appearance. Therefore, it is necessary to release the engagement, detach the upholstery material from the engaging member, and then attach another upholstery material to the engaging member.
Patent Document 4 discloses a method of precisely positioning an upholstery material to a cushion member, in which an array of loop engaging elements is sewn to the back surface of an upholstery material and a guide plate is disposed along the array of loop engaging elements, and the guide plate is inserted into a slit formed on the bottom of groove on the cushion member to place the upholstery material in precise position.
However, when the cushion member has a three-dimensionally curved complex surface (generally, a seat for luxury cars has a three-dimensionally curved complex surface for fitting to occupant's body), it is necessary to cut or bend the guide plate so as to fit the three-dimensionally curved surface. If the guide plate is used in the seat area or the back, the occupant feels uncomfortable because of rigid guide plate. Therefore, the position to which the guide plate is applicable is limited. In addition, the heavy guide plate increases the weight of car body and also increases production costs.
Patent Document 1: Japanese Patent 3255384
Patent Document 2: JP 2003-79976A
Patent Document 3: JP 2005-418A
Patent Document 4: JP 2006-141619A